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E39 (1997 - 2003) The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

I've read a lot of ABS DSC threads on this board and others and have found some really good writeups on how to diagnose problems with the ABS/ASC-T system.

I, like others, have an intermittent problem where the warning lights come on and then clear away when shutting down the engine. They warning lights may come back in 10 minutes or 1 hour or 1 day with no DTC being set.

However, the OP should be advised that the fancy schmancy scan tools often (if not always) report erroneous faults (e.g., the errant P0500 Vehicle Speed Sensor Malfunction or the errant 51 brake pressure sensor codes, both of which I had and both of which were dead wrong).

See why in this often-repeated explanation of the problem with the fancy schmancy diagnostic tools!

Quote:

Originally Posted by bill 540iman

The main point is that any diagnostic equipment that does not test by going between the sensors and the module simply can not definitively see a bad module from a bad sensor. It is as simple as stating that a blood pressure cuff can not diagnose whether high blood pressure reading at a cuff is because of a faulty heart or a clotted artery. You must somehow get readings I suspect (certainly not a Dr.!) between the heart valves or whatever you do to isolate. If your Indy or dealer hooks up to your OBDII port or your 20 pin and definitively tells you that you have a bad wheel speed sensor, that person is full of doo-doo. Only thing you can diagnose correctly 100% of the time from either of these two points is a bad module due to a communication error or similar. They can not tell a bad input (sensor) from a bad module at these test points.

Since the fault codes reported are often (if not always) erroneous, the OP will be interested in the fact that 'most' of the ABS BRAKE DSC trifecta repairs consist of the following (trivial) tests & procedures:

1. Take ten minutes to test the four wheel speed sensors from the engine bay using a 'good' DMM (the Fluke 75 is known to work well).

2. If any are bad, test again at the wheel; if still bad, then replace the errant wheel speed sensor.

3. If all four wheel speed sensors test good, then some people test by running a hair dryer on the ABS control module in the garage and/or spraying freeze spray, to cause the trifecta to appear and disappear at will (because the steel wire lifts ever so slightly off the gold bondpad with temperature changes).

4. Some people even open up the ABS control module and use a magnetized needle to test the steel power wires for connection to their gold bondpad.

5. Either way, the solution is generally to send the ABS control module out to the rebuilders for 'repair'. If you do go that route, PLEASE contact the rebuilders when your particular ABS control module is on their test jig and ASK them what they found wrong.

We're trying to collect that anecdotal evidence (which appears, to me, to contain mostly lies from the rebuilders) over in the canonical ABS DSC BRAKE trifecta thread.

More details that you could possibly ask for are in this thread:
- E39 ABS DIYNote: Read the whole thread - not just that single post #48.

I decided to go to a local indy who has diagnostic equipment that could read the ABS fault code instead of continuing to chase the intermittent problem.

I actually began to test the sensors myself. They all showed to be working fine which was puzzling. At this point I decided chasing an intermittent problem could be a long process so I decided to find out what the actual stored fault was. The fault was being triggered by one of the front sensors.

Of course I did ! I slipped him a 20 for his time which wasn't very long.

Quote:

Originally Posted by bluebee

I am suspicious that a good DMM wouldn't have told you what you ended up paying an Indy to tell you (and for less money than the cost of the good DMM).

.

Are you implying my volt meter isn't good ? Careful on that statement... I'm sure its a good one.

One thing you keep overlooking is the fact that this was an intermittent problem. I wanted to know what was tripping the warning when it did show itself. It wasn't a situation where the fault was constantly there to detect, therefore, it didn't show when the sensor was measured.

Don't confuse my solution to the problem with my opinion of the writeups and documentation on the subject. They are excellent for understanding and troubleshooting without reading the fault codes.

You used "warning lights" (plural) in your OP. I am assuming by that you mean the combination of the DSC warning light, the amber BRAKE warning light and the amber ABS warning light. If so, be advised that the wheel speed sensor "fix" lasted me all of two weeks. After I read up on the wealth of great info here about the ABS module and had it sent off for repair, the problem has been resolved since. Good luck.

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Quote:

Originally Posted by Fudman

For me, the e39 is the ... best balance of luxury ... performance ... good looks and class. Sort of the Catherine Deneuve of cars, if you get my drift.

You used "warning lights" (plural) in your OP. I am assuming by that you mean the combination of the DSC warning light, the amber BRAKE warning light and the amber ABS warning light. If so, be advised that the wheel speed sensor "fix" lasted me all of two weeks. After I read up on the wealth of great info here about the ABS module and had it sent off for repair, the problem has been resolved since. Good luck.

Sorry to hear of your misfortune.

I didn't have 3 warning lights.

The fact of the matter is that the problem I encountered is most definitey fixed.

It took the indy 2, maybe 3 minutes to pull the code on screen... no fancy report.

This was an intermittent problem. I wanted to know what was tripping the warning when it did show itself. It wasn't a situation where the fault was constantly there to detect, therefore, it didn't show when the sensor was measured.

I chose to solve the problem as described. Perhaps someone else may do the same BEFORE sending their unit out for a rebuild.

For many, including me, the light trifecta was also an intermittent problem. It's okay to want to trust your mechanic implicitly, though please understand that the lack of specifics makes many of us (who've seen and helped diagnose this issue repeatedly) skeptical.

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Quote:

Originally Posted by Fudman

For me, the e39 is the ... best balance of luxury ... performance ... good looks and class. Sort of the Catherine Deneuve of cars, if you get my drift.

.... makes many of us (who've seen and helped diagnose this issue repeatedly) skeptical.

I'm not going to even bother with that statement.

No, I didn't want to spend time putting a hair dryer to the module.... or buying freezing spray... or opening up the module and playing with the wiring.

I chose to solve the problem as described. It seems that my choice of not following a certain developed methodology is causing certain people to be flustered for not following that methodology... thats unfortunate.

I don't think anyone's flustered, and we are all happy that the problem is most definitely fixed. What we were hoping to ascertain from you were the sensor test results, the type of scanner used, what the fault code actually was, etc. - or any details at all really - for the benefit of the vast pool of knowledge that bluebee so meticulously maintains.

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Quote:

Originally Posted by Fudman

For me, the e39 is the ... best balance of luxury ... performance ... good looks and class. Sort of the Catherine Deneuve of cars, if you get my drift.

I don't think anyone's flustered, and we are all happy that the problem is most definitely fixed. ... What we were hoping to ascertain from you were the sensor test results, the type of scanner used, what the fault code actually was, etc. - or any details at all really - for the benefit of the ... pool of knowledge

You seem to have a 'need' to jump into any thread that has the word ABS in it ... or worse, hijack someone elses thread...

Its obvious that its offended some by the methodology used - thats unfortunate and clear with some of the remarks made in this thread.

Exactly how did you come to the conclusion that your methodology has offended anyone when you haven't provided any specifics as to how you declared the issue most definitely fixed other than 1.) trust your indy when he told you it was a wheel speed sensor and 2.) gave him $20?

There are two things we do know for certain: You're the one who created a thread and requested assistance, and you can rest assured that no one who offered it to you in this thread will be doing so again.

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Quote:

Originally Posted by Fudman

For me, the e39 is the ... best balance of luxury ... performance ... good looks and class. Sort of the Catherine Deneuve of cars, if you get my drift.